In the past, turf maintenance vehicles generally employed mechanical systems to control the vehicle's various cutting functions, engine functions, etc. However, as electronic controllers have become more robust and sophisticated, it has been recognized that the control of a turf maintenance vehicle's various systems can be enhanced by utilizing electronic controllers. Accordingly, various electronic controllers have been utilized to monitor and/or control various functions on turf maintenance vehicles.
A first example of such a vehicle utilizing an electronic controller is U.S. Pat. No. 5,394,678 titled "Electronic Control for Turf Maintenance Vehicle" issued to Lonn et al and assigned to The Toro Company (the assignee of the present invention). This patent generally discloses use of an electronic controller for maintaining a predetermined cutting "clip" at varying ground speeds, heights of cut, and other changed conditions for a turf maintenance vehicle.
A second example of an electronic controller used on a turf maintenance vehicle is disclosed in U.S. Pat. No. 5,497,604, issued to Lonn et al and assigned to The Toro Company (the assignee of the present invention). This patent generally illustrates use of an electronic controller device to implement a "supervisor switch" for a turf maintenance vehicle. The switch automatically provides for maintaining an acceptable ground speed during cutting operations of a turf mower.
A third example which utilizes an electronic controller is disclosed in U.S. patent application Ser. No. 08/375,760 entitled "Electronic Liquid Level Detector", filed Jan. 20, 1995 to Lonn et al and assigned to The Toro Company (the assignee of the present invention). This application generally discloses a hydraulic fluid level detector. An electronic controller is used in connection with a measuring device for determining changes in the volume of hydraulic fluid in a reservoir of the type utilized on a turf maintenance vehicle. The processor monitors changes in volume in order to determine whether a leak condition exists (i.e., whether hydraulic fluid is escaping the reservoir).
In each of the foregoing examples (the disclosures of which are hereby incorporated herein by reference and made a part hereof), the electronic controller utilizes a plurality of inputs and outputs to monitor the various conditions, to process the information, and to provide output to regulate the process and/or to warn the operator of improper conditions. It will be appreciated by those skilled in the art that, in many instances, it is beneficial for controllers located on the same turf vehicle to share information (either inputs, computed outputs, or error conditions).
Generally in the past, a single electronic controller was utilized to perform several functions. In these instances, however, reprogramming was required for the single processor to perform the various control functions. Alternatively, a different software program was required to be loaded into the controller--based on the other optional controller based devices located on board the turf maintenance vehicle and/or additional features. Both of these approaches, however, constituted a "fixed electronics architecture." Although such an approach may be implemented, this type of architecture has several drawbacks.
First, the issue of programmability discussed above creates drawbacks since a "fixed" program device is not compatible with normal product enhancement processes. By way of example, improvements are not easy to implement with these devices because often the electronic hardware must be replaced. Additionally, if non-interchangeable enhancements are implemented, then backward compatibility for service may be a problem.
Second, with this type of architecture it is difficult to determine the correct processor size from a commercial standpoint for any given electronic controller application (e.g., from a cost and upward enhancement standpoint). For example, if the controller is optimized for one application, then that controller may have more or less capability than is needed for the next application or enhancement. This creates a problem during the design process since the electronic controller must initially be designed with excess capacity. The alternative is to eliminate the excess capacity at the expense of limiting functionality or upward enhancements.
Third, it is oftentimes desirable to have the ability to share information among the various intelligent electronic processor devices located on-board. Over time, the ability to communicate may afford a reduction in costs (e.g., elimination of redundant sensor devices) and may promote further integrating on-board systems.
Therefore, there exists a need in the art to develop a system wherein the various electronic controller devices located on a turf maintenance vehicle are connected to a common bus, automatically polled to determine which controllers are present/operative, recorded by building a list of the various responding controllers connected to the bus, and connected to exchange information. The present invention directly addresses and overcomes the shortcomings of the prior art.